Subject: [Asrg] 3b. SMTP Session Verification - explicit source routes

From: "Za'mbori, Zolta'n" <[email-masked]>
Date: Sat, 17 Jan 2004 15:54:02 +0100

RFC2821, 3.7 Relaying:

"In general, the availability of Mail eXchanger records in the domain
name system [22, 27] makes the use of explicit source routes in the
Internet mail system unnecessary" (in the RCPT command).

Is it true that because of "the availability of designated sender 
records in the domain name system makes the use of explicit source 
routes in the Internet mail system necessary" (in the MAIL command)?

z2

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From: "Jon Kyme" <[email-masked]>
Date: Sat, 17 Jan 2004 16:52:15 +0000

> routes in the Internet mail system necessary" (in the MAIL command)?

If you want forwarding / 3rd party relaying to work. I believe you're
right. Pretty much.
See: http://spf.pobox.com/objections.html

As you suggest - RMX type systems look a lot like the mirror-image of MX.  

But of course, these source routes MUST NOT be truly *explicit* - or a new
channel for abuse is opened up - the "bounce path". Without a
complementary, and secure, Sender Rewriting Scheme (or something), I can't
see that a system like SPF is much use in the real world.

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